Protective covering and method of producing such covering



Dec. 22, 1931. H. c. sTEARNs 1,837,733

PROTECTIVE COVERING AND METHOD OF PRODUCING SUCH COVERING F11-ed Apr-1119, 1930 rPaxierlted Dec. 22, 1931 UNITED STATE-s PATENT oFFlcE.

HARRY C. STEARNS, OFOAK PARK, LLINOIS, ASSIGNOR TO WESTERN ELECTRIC COM-PANY, INCORPORATED, OF NEW YORK,

PROTECTIVE COVERING AND METHOD OF yPJEtODU'CINGr SUCH COVERINGapplication mea April 19,

This invention relates to a protective covering and a method ofproducing such a covering.

The primary objects of this invention are to provide an improvedprotective covering anda method of producing the same in an eiiicient,economical and expeditious manner.

In accordance with the objects of this invention as practiced in oneembodiment thereof in connection with the manufacture of protectivecoverings or envelopes, a cellulose derivative material is arranged inconvolution form. Thereafter a portion of the ma-m terial is subjectedto a solvent for coalescing the material to effect securement of thesubjected portion.

Specifically this invention contemplates the provision of an insulatingcovering for an electrical coil and as practicedin this connectioncellulose material in strand form is arranged in a plurality of layersof adjacent helices about the periphery of the coil, the inner end ofthe strand being intermediate the ends of the coil. Upon completion ofthe serving operation, which terminates at a point intermediate the endsof the coil, the unwound portion of .the strand material is severed andthe free end of the helically applied portion thereof is secured fromunwinding by dispensing/a small quantity of solvent to dissolve andcoalesce the-material,- at the point where it is desired to sever thematerial and secure the free end of the helically applied portionthereof. Thereafter the en- 35 tire cellulose material forming the coveris treated with a solvent to dissolve portions thereof and effectcomplete coalescence ofthe naterial and produce an imperforate enveo e.j

I(,)ther 'objects and advantages of this in vention will more full vappear from the following description, ta en in connection with theaccompanying drawings, wherein Fig. 1 is an elevational view of anelectrical coil having a covering embodying-the invention and producedaccording to the improved method, part of the coil being broken away tomore clearly illustrate the details of the structure;

50 Fig. 2 is an enlarged view of a coil show- N. Y., A. CORPORATION OFNEW YOE'K 1930. seran No. 445,815

ing the method of applying the coveriri thereto, only so much of theapparatus use being shown as is necessary to a complete understanding ofthis invention; f Fig. 3 is a fragmentary vertical sectional 55 View onthe line 3 3 of Fig. 2; Fig. 4 is an enlarged fragmentary detail Viewtaken on the line 4 4 of Fig. 3, and Fig. 5 is an enlarged fragmentaryview of the coil shown in `Fig. 1, showing the -improved cover of thisinvention in various stages of completion. l rlhe type of fiber orstrand employed may be of any ber or strand of a cellulose nature, suchas the cellulose derivatives, which in a manner to be described latermay be treated With a solvent to produce the effect desired. Examples ofsuch materials are the strands of artificial silk which are made up of apluralityA of synthetic filaments or ends. These strands may be employedfor practicing the invention without any additional treatment. Strandsof natural vegetable or animal'iibers, such as cotton or silk threads,may be employed but theymust be impregnated with a cellulose derivative,such as 4nitro-cellulose or celluloseacetate, before they are incondition for use. When the type of strand tobe used has been selected,lengths thereof may be arranged in an unwoven manner, such as solely inan unwoven warp formation, in the'formfof a web or in whateverotherformis desired, which will permit the successful treatment as willbedescribed hereinafter.

When employed to form a 4waterproof and insulating cover foranelectrical conductive winding 10 of an electrical coil (Figs. 1, 2 and3), designated generally by the numeral 11 having a core 12 andendpieces or spool 90 .heads 13, the strand indicated at 14 ispreferably arranged in a series of adjacent helices 15 comprising one ormore layers. Re-

ferring particularly to Fig. 2 wherein the improved cover is shown inprocess of being produced, 17 and 18 indicate a rotatable spindle and achucking element, respectively, adapted to receive the core 12 carryingthe electrically conductive winding 10 thereon-l therebetween and rotatethe same during the 10o" application of the cellulose strand 14C aroundthe coil. A. supply (not shown) of the strand 14 is mounted in anyconvenient manner so as to permit the strand to be freely withdrawntherefrom upon the application of tension exerted thereon by therotation of the coil 1l in the manner previously described. Suitabledistributing means of a known type (notshown) maybe employed between thestrand supply and the periphery of the coil l0 for distributing thestrand ll longitudinally of the coil in adjacent helices l5. The servingof the cellulose strandjld is preferably begun at an appreciabledistance from either of the heads 13, for instance at the pointindicated at 20, and is continued to the left head 13, whereupon theserving of the strand is continued across the entire width of the coilto the right head 13, and then back to the point 20, thus serving twolayers of helices l5 of the cellulose strand la around the winding 10.

Positioned immediately above the periphery of the coil 11 and in linewith the point 20 where the beginning and ending of the servingoperationoccurs isa liquid dispens ing apparatus (not shown) provided with anozzle 23. After serving the strand ld in the manner previouslydescribed to the coil ll the rotatable spindle and chuclr l? and 18,respectively, are stopped and the operator actuates the dispensingapparatus and a small quantity of solvent for the cellulose derivativematerial is applied through the nozzle 23 to a portion of the strand atthe point 20 (Figs. 2, 3 and d), which contemporaneously severs bydissolving the cellulose strand material from the supply and coalescesthe free end of the strand served upon the coil to an adjacent portionof the strand to edect the securement thereof. lhis method of -securingthe free end of the served cellulose strand providesa smooth peripheralsurface to the coil ll and avoids any appreciable shrinkage of thestrand at the point of securement sumcient to cause the end of thestrand to brealr loose. At the time of dispensing the solvent onto thestrand at the point 20 it is to be understood that the strand from thesupply thereof (not shown) is under a minimum amount of tensionsufiicient to separate the strand at the point 2G upon being dissolvedby 'the solvent applied theret lhe solvent employed may be of any of thewell known solvents for the cellulose derivatives. Acetone, however, ispreferred be cause this material is a good solvent for both celluloseacetate and cellulose nitrate and is easily handled.. Other solvents,however, which may be employed are a mixture of ether and alcohol.,tetrachloralethane, ethylacetate, diacetone alcohol, methylethyleketonor benzol acetate.

The next step in the method of producing` the improved cover consists insubjecting the Leary/aa assembled lengths of strands of cellulosematerial to a solvent of the nature hereinbefore referred to to producean imperforate cover. The solvent may be applied in a number of ways,such ,as dipping the cover alone or in the specific cover describedherein the cover and the coil enclosed therein in a bath of the solvent.As another exampleythe covers may be sprayed with a solvent or subjectedto the vapor of a solvent during the boiling thereof. In any case theclosely associated cellulose strands become partially dissolved or fusedin a manner which might be termed autogenous agglutination. 'lhe closelyassociated cellulose strands thus coalesce or adhere to each other andafter being dried to evaporate all of the solvent the finishedimperforate covering presents the appearance as shown at 24 in Figs. land 5. rlhe covering when completed is homogeneous and shiny on onesurface where the solvent action has been applied to the cellulosestrands,but on the opposite portion of the covering the strands willstill be found to retain their original individual character.

The term cellulose material is used in the appended claims to refereither to fibers or strands composed entirely or partially of syntheticfilaments or to natural fibers or strands impregnated with a cellulosederivative, and the term solvent as employed in the appended claims isintended to include plasticizers as well as true solvents.

What is claimed is:

l. A method of producing' a protective covering for a body, whichconsists in applying cellulose material in strand form from a supplythereof around the body, and subjecting a portion of the material to asolvent for severing it from the supplyl 2.v A method .of producing aprotective covering for a body, which consists in applyingcellulosematerial in strand form. from a supply thereof around the body,and sub jecting a portion of the material to a solvent forcontemporaneously severing it from the supply and coalescing thematerial at its free applied end to an adjacent portion of the materialto effect the secureinent thereof.

method of producing a protective covering for a body, which consists inapplying cellulose material in strand form from a supply thereof in aplurality of adjacent helices around the body, subjecting a portion ofthe material to a solvent for contemporaneously severing it from thesupply and coalesc/ing the material at its free applied end to anadjacent portion of the material to edect the securement thereof, andsubjecting the helically applied material to a solvent to coalesce theadjacent helices.

el. A method of producing a protective covering for an electrical coil,which consists in applying cellulose material in strand form from asupply thereof in a plurality of adjacent helices around the coiledconductor, subjecting a portion of the material to a solvent forsevering it from the supply, and

subjecting the helically applied material to a solvent to coalesce theadjacent helices.

5. A method of producing a protective covering for an electrical coil,which consists in applying cellulose material in strand form from asupply thereof in a plurality of layers of adjacent helices around thecoil, the ends of the strand being intermediate the' ends of the coil,and subjecting a portion of the material to a asolvent forcontemporaneously severing it from the supply and coalescing thematerial at its `free applied end to an adjacent portion of the materialto eiect the securement thereof.

6. A protective covering for a body, consisting of a plurality of layersof helices of 'cellulose strand surrounding the body, the

ends vof the strand being intermediate the ends of the body and theouter end of the strand coalesced to an adjacent portion.

"7. A protective covering for an electrical coil, consisting of aplurality of layers of helices of cellulose strand surrounding the coil,the ends of the strand being intermediate the ends of the coil,adjacenthelices of the outer layer and the outer end of the strand beingcoalesced.

In Witness whereof, I hereunto subscribe my name this 9th da of April,A. D. 1930.

HA RY C. STEARNS.

